Edwaed l



(No Model.)

B. L. WILSON.

TELEPHONE TRANSMITTER.

Patehted Apr. 3, 1883.

Inn/e Yoko 7?- UNITED STATES PATENT OFFICE.

EDVARD L. W'ILSON, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO THE AMERHJANBELL TELEPHONE COMPANY, OF SAME PLACE.

TELEPHONE-TRANSM ITTER.

SPECIFICATION forming part of Letters Patent No. 275,310, dated April 3,1883.

Application filed January 27, 1883. (No model.)

I 0 all whom it may concern:

Be it known that I, EDWARD L. WILSON, of Boston, in the county ofSuffolk and State of Massachusetts, have invented certain Improvementsin Telephone-Transmitters, of which the following is a specification.

My invention is an improvement in micro phonic or contacttelephones-such as are in common use as transmittersand its objects,broadly stated, are to provide an improved method of supporting thediaphragm in place to minimize the cost, to simplify construction, andto dispense with parts which, while useful, by reason of their fragilityand uncertainty of operation, are liable to cause annoyance both inconstruction and exploitation. In such transmittingtclephones it is wellknown that the current of a voltaic battery passing through two contactelectrodes is varied. The vibrations of the diaphragm, developed by theaction of the voice, thus act directly upon the contact-electrodes,varying their pressure upon one another, as a penultimate consequenceproducing variations in the resistance of the circuit, and as anultimate consequence producing variations of strength in the currentflowing in the circuit. Experience has demonstrated that alltransmitting-diapbragms have distinct initial vibrations of their own,and when vibrations are produced in them from any external cause-forexample, by vocal utterances in near proximity to them-it is difficult,and sometimes impossible, to obtain distinctness in the speechreproduced by the receiving-telephone unless the initial vibrations arefirst dampened or subdued. It has been customary to deaden theseunnecessary and pernicious vibrations by clamping one edge of thediaphragm firmly to its seat by a metal clip, and by causing the otheredge to be elastically held by a thin steel spring fastened at one endto thet'rame of the diaphragmseat, and pressing with its free end, whichis covered with a pad of some textile or elastic non-conduct0r-such asrubber or clothupon the inner face of the diaphragm. This device. isused ordinarily in the well-known Blake transmitter, and is usuallycalled a damping-spring. In practice these damping-springs have beenproductive of much trouble and annoyance in the course of manufactureand process of testing the transmitters, as well as during the operativelife-time of the same. It has been found difficult to procure steel ofthe exact texture and temper required, and when such springs areprocured they are frequently broken during the process of adjustment.which is a work of great delicacy. Moreover, when at work it is more orless diffioult to maintain a proper adjustment. By my invention 1 amenabled to dispense with the damping-spring, and may, if desired,dispense also with other delicate parts, as will be hereinaltersuccinctly described.

My invention consists chiefly in providing a magnetic support or seatfor the diaphragm, and in combining the same with the other parts of theinstrument in such a manner that no other means of holding or dampingthe diaphragm are necessary.

In the drawings, which form a part of this specification, for greaterperspicuity I show the working parts of an ordinary Blake transmitter incontrast with a similar instrument furnished with my improvement.

Figure l is an elevation of the working parts of a Blake transmitterseen fromthe rear. Fig. 2 is a sectional side elevation of the workingparts of the same on the line 00 00, Fig. 1. Fig. 3 is a verticalsection, showing my improvement. Fig. 4 is a sectional elevation on thelineyyot' Fig. 3, looking from theinside. Fig. 5 is a rear elevation,and Fig. 6 a section on the line 2 z, of another form of microphonictransmitter, also furnished with my improvewent.

I will first briefly describe the Blake transmitter, which is depictedin Figs. 1 and 2.

A vibrative diaphragm, D, fringed with a rubber pad, (I, which overlapsboth edges, is supported in a ring-seat formed in a metal frame, A,which also has at top and bottom a projecting piece or lug, S S From theupper lug, S, by means of a flat spring, a, an adjusting-lever, B, issuspended, which carries on an arm extending inward from its upperextremity the two contact-electrodes ot' the circuit 0 and O, the formerbeinga small piece of platinum and the latter a button ot'earbon in acasing of metal. The platinum electrode is suspended from the arm of thelever by a light spring, 0, while the carbon is similarly suspended by aheavier spring, b, Which is in electrical contact with theadjusting-lever, the spring 0' being insulated therefrom, so that theonly electrical contact between the two springs is made through theplatinum and carbon electrodes. An adjusting-screw, R, passes throughthe lower lug, S and bears against the angular extremity of the lever B,andis screwed up until the platinum electrode is broughtinto contactwith the diaphragm, and when so placed any vibration of the diaphragm isparticipated in by the electrode. A metal clamp,f, screwed to the ironframe presses tightly on the padded rim of the diaphragm, and adamping-spring, g, on the opposite side, is similarly secured, and byits free end, which is padded, presses on the diaphragm near its centerand averts or obviates any noxious or unnecessary or unwarrantedvibration.

In my improvement I replace the metal frame constituting the ring-seatby a pair of semicircular bar-magnets, M M, having like poles injuxtaposition, as shown in Fig. 4, wherein N N represent the two northand S S the two south poles. These magnets are held together and inplace by brass brackets or standards 6, which are screwed thereto at topand bottom, and which may also be screwed to the front board of thetransmitter-box. The holes a are for the latter purpose. From the upperbracket extends the lug E and from the lower bracket the complementarylug E, which both subserve the same purpose, as in the ordinary Blaketransmitter. The dampingspring 9 and metal clamp fare both entirelydispensed with, since it is tound that by forming the diaphragm-seat ofmagnetic material the diaphragm is both efficiently supported andcontrolled.

In Figs. 5 and 6 I show another form of contact-telephone to which myinvention is applied. In this form also the diaphragm is held bymagnetism alone, and the platinum electrode, with its delicatesuspending-spring, is superseded by a condnoting-electrode, G, rigidlysecured tothediapragm D. This islightly pressed upon by the usualspring-suspended carbon button, 0, and the initial pressure is given bycombining an auxiliary spring,j, riveted at its upper end to thesuspending-spring of the button, with a metal bar, F, fastened at itsend thereof to the abutment or lug E, and provided at its lower and freeend with an adjusting-screw, k, passing through the said bar and againstthe free end of the auxiliary spring. By means of this device a delicatebut firm initial pressure may be obtained between the electrodes.

The electrode U is brought into the voltaic circuit by fastening one ofthe wires thcreot'to the diaphragm, as shown in Fig. 5. In this form ofinstrumentthcre is a small bent piece, It, fastened to the lowerbracket, 0, for attaching the transmitter to the front board of thetransmitter-box.

Although I have shown the magnets forming the frame or seat of thediaphragm as being semicircular, I may, without departing from thespirit of my invention, form the same of a complete or closed circularmagnet; or I may use four quandrantal magnets, it being evident that inthis case form is not of paramount importance. I may also, if I soelect, place opposite instead of like poles in juxtaposition.

I claim- 1. In a battery-telephone, the combination, with the diaphragm,of a permanently-magnetic frame or support adapted by the force of themagnetism to hold the edges of said diaphragm, substantially asdescribed.

2. In a battery or variable-resistance telephone, the combination, withthe diaphragm, of a magnetic frame orsupport, the magnetism of saidframe or support being independent of the current upon the line,substantially as described.

3. The combination of the diaphram, magnetic frame therefor andcontact-pieces or electrodes, substantially as described.

at. In a telephone, the combination, with the diaphragm, of a frame orsupport comprising one or more permanent magnets, substantially asdescribed.

5. In a telephone, the combination, with the vibratory diaphragm, of aseat or support therefor comprising curved or semicircular magnets, sodisposed as to attract and hold the diaphragm at its edges only,substantially as described.

(5. A telephone-transit]itter consisting of a vibrating diaphragm, acircular or double semicircular magnetic frame therefor, brackets ofnon-magnetic metal attached thereto-one on each side-and forming apartial ring-seat for the diaphragm, combined with the circuitelectrodescomposing the variable resistance, and devices for adjusting the initialpressure of the same, substantially as hereinbefore described.

7. The combination, substantially as hereinbefore described, ot' avibrating diaphragm adapted to control the electrodes of avariableresistance transmitter, with two semicircular magnets placedwith like poles in juxtaposition, and two non-magneticyoke-piecestherefor, uniting the said magnets and forming thereon a seat or supportfor the said diaphragm, in which it is magnetically held.

8. The combination, substantially as described hereinbefore, ofavibrating diaphragm, a frame composed of two semicircular magnets heldtogether bynon-magnetic yokes, the said yokes extending inwardly andforming, with the magnetic frame, a holder or seat for the diaphragm,whereby the said diaphragm is freed during its operation from hurtfulvibrations, independently of the employment of a damping-spring.

Intestimony whereofI have signed my name to this specification, in thepresence of two subscribing witnesses, this 25th day of January, 1883.

EDWD. L. WVILSON.

Witnesses:

J. H. OHEEVER, GEO. WILLIs PIERCE.

